Burner apparatus control mechanism



Feb. 9, 1937. I F, 5 DENISON ET AL 2,070,118

BURNER APPARATUS CONTROL MECHANISM Filed June 18, 1931 5 Sheets-Sheet l fig. i

INVENTORS 13 FREDERICK 5. DENISON HN F. KRIECHBAUM I 57/231 4% WM ATTOHNEV$ 9, 1937- F. s. DENISON ET AL BURNER APPARATUS CONTROL MECHANISM Filed June 18, 1931 5 Sheets-Sheet 2 I NVENTORS N NM. N E H .6 w N am if 0 J Feb, 9, 1937. F. s. DENISON ET AL BURNER APPARATUS CONTROL MECHANISM Filed June 18, 1951 5 Sheets-Sheet 5 u w TQIQA. N W VEH 7 .6 T 15M &PA 5 I @mw/ mm Feb. 9, 1937. s DEMON ET AL 2,070,118

BURNER APPARATUS CONTROL MECHANISM Filed June 18, 1931 5 Sheets-Sheet 4 HOT LINE GROUND LINE R IeN/nmv RATCHET 1 a MOTOR TIME 5WITCH 57'. JIV. NFC/i. 0N HEHT/NG- W7C! 05135 BEFORE 16 OPE/Y6 O/V COOL/N6- /'7 OPE/Vfi'fiEf'O/FE l6 COSES).

IN VENTORS FREDERICK 5. DENISON J N P. HRIEGHBAUM Y M Arvoalvgvs Patented Feb. 9, 1937 UNITED STATES PATENT OFFICE BURNER APPARATUS CONTROL MECHANISM Application June 18, 1931, Serial No. 545,350

15 Claims.

This invention relates to control systems for heat producing apparatus, and has as an important object the provision of 'a burner control system, by means of which a series of trial ignition operations. can be obtained at the end of which series, if flame is not produced, the entire system is automatically rendered inoperative. Another object is to provide a pre-ignition timing period before fuel delivery is started, and also to provide a. predetermined post-ignition timing period after fuel delivery starts and during such delivery. Other objects are: to maintain ignition means activation until combustion results, or until combustion fails after repeated trials; to stop the burner motor substantially immediately, in case of unsuccessful combustion after repeated ignition trials; to provide a timed interval between thestopping of fuel feed, and the resumption of the same between the trial 20 ignitiOn periods; and to provide means whereby on power failure the system will, on resumption of power, automatically re-cycle after a predetermined standby interval; and to provide means whereby on flame failure, after successful combustion, fuel feed is interrupted, the burner motor is stopped, and re-cycling occurs after a predetermined standby" period.

The present invention finds valuable application in controlling oil .burners of the rotary or vertical shaft revolving cup type, in conjunction with a resistance ignition element. This element is a wide thick band of metal ribbon. A special current regulating transformer is used, and theignition element ordinarily receives approximately eighty amperes at four volts. It requires from a minute to a minute and a half for the temperature of this ignition element to rise sufficiently to ignite oil, and after having reached this point, if its temperature is lowered too much,

ignition will not be successful. If the temperature is too great, the ribbon deteriorates rapidly. The system is operated as follows: The ribbon is energized for a period of one and one-half to two minutes while the oil burner motor is not running and, therefore, not delivering oil, nor blowing air across the ignition element to interfere with the heating operation. The burner motor is then operated, the oil valve is opened and a spray of mixed oil and air is thrown into the fire box, and in close proximity to the ignition clement. After about a minute (during'which ignition frequently does not occur) the burner motor is rendered inoperative.

In the present device, the ignition means is not de-activated after ignition failure on the first trial, but one or more additional trials are made, while ignition means energization is constantly maintained. During the inactive periodof the motor, the ignition means gains somewhat in temperature and has a tendency to vaporize the oil close to it, and produce little flames immediately around it. This is what is known as a wicking action. When the burner motor is activated for the second time and oil is again delivered, there is usually a small amount of flame present around the ignition element, and this flame, in conjunction with the added heat of the element itself, combines to ignite the main oil spray.

An important feature of this invention is, therefore, to-provide means for producing repeated trial-ignition operations of the system while maintaining ignition means activation, at the end of the last of which operations if flame is not produced, the system as a whole is rendered inoperative.

Features of the invention include all details of construction, as well as the broader ideas of means inherent in the disclosure, and combinations and sub-combinations of elements of the system.

Objects, features and advantages of the invention will be set forth in the description of the drawings forming a part of this application, and in said drawings Figure 1 is a face view of the panel;

Figure 2 is a vertical section taken through the ratchet mechanism, on line 22 of Figure 1, looking in the direction of the arrow;

Figure 3 is a plan view further illustrating the ratchet mechanism, and showing it in its normal or starting position;

Figure 4 is a, vertical section on line 4-4 of Figure 1 showing the position of the ratchet mechanism when the first relay is closed, and showing the pawl of the second relay conditioned for ratcheting action on closure of said second relay;

Figure 5 is a longitudinal vertical section through the flame responsive switch, pyrostat" or stack thermostat, on line 5-5 of Figure 6;

Figure 6 is a face view of the flame responsive switching device, showing the switches positioned as when the thermal element is cold;

Figure 7 is a diagrammatic view illustrating the circuit connections of the system;

Figure 8 is a front view illustrating a modiflcation of the ratcheting mechanism for opening the safety contact or master switch, with the parts positioned as when both relays are open;

iii

Figure 9 is a top plan view of Figure 8, corresponding to Figure 1; l

Figure 10 is a vertical section on line Ill-l of Figure 8 with relay No. 1 energized;

Figure 11 -is a section on line I li I of Figure 8, showing the parts in side elevation, with part of the driving pawl-operating arm and pawl broken away; and

Figure 12 is an enlarged detail elevation showing the position of the driving pawl arm and pawl, when both relays are closed, and further illustrating how over-run of the ratchet wheel is prevented.

Before describing in detail the various devices of the system, attention is called to the principal elements of this embodiment of the invention which are: two relays or their equivalents designated N01 1 and No. 2 (also referred to as first and second) which relays respectively control ignition means generally indicated at i, and fuel control .means generally indicated at 2; a safety switch 3, which is adapted, when opened to render the entire system inoperative; ratcheting means controlled by said relays for controlling the safety or master switch 3 to open it on failure to produce combustion following repeated trial ignition operations; a thermal time switch including contacts l3, I4; switch arms l5, I5 controlling the contacts; bimetallic elements 28, 30 controlling the arms, and heater 4 controlling bimetallic element 28, said'heater being controlled by circuits in turn controlled by the relays, and being adapted by its heating and cooling effects to control its contacts l3, [4 which are in the thermostatic circuit, and which control relay No. 2; a flame responsive device generally indicated at 5 having contacts l6, l1 which are overlappingly controlled on rise of temperature, and non-overlappingly controlled on fall of temperature, for controlling the relay circuits; a room thermostat which controls the relays and has a movable element R, and contacts W-B sequentially engageable by said element R; two contacts 6'| in the thermostatic circuit, and a third contact 8 controlling energization of the ignition means I, all controlled by said first relay; contacts controlled by the second relay as follows: contacts 9- lll overlappingly controlled in bothdirections and in the thermostatic circuit; and a contact II also in the thermostatic circuit; and a contact I2 controlling the burner motor, or fuel feed apparatus 2; contacts |6--I1 of the flame responsive device 5, overlappingly controlled on temperature rise and non-overlappingly controlled on temperature fall; and various circuits by which the operations of the foregoing elements are co-ordinated. The circuits are not at this time described nor referred to by reference numerals, but detailed explanatory and numerical reference to the circuits is made under the headings Operation..

An important device in this system is one which is controlled by the two relays (one controlling the ignition means and the other the motor) and which, in turn, controls the safety switch 3, to open the switch after a plurality of opening and closing motions of that relay which controls the motor, and while the ignition means controlling relay is energized. It will be understood that in the present system ignition meansactivationis maintained throughout the plural trial ignition periods, but that the burner motor is always deactivated after a failure to produce flame, and that after such motor de-activation a stand-by period is provided so that explosive gases may be dissipated before the next trial ignition operation is initiated.

One form of device for obtaining the opening of the safety contact or switch 3 after a series of trial ignition periods is shown in Figures 1 to 4. In these figures is also illustrated the relay panel.

Numeral 25 generally indicates a panel upon trols a bimetallic element 28, which abuts a pin 29 carried by bimetallic compensating arm 30. This arm 30 is mounted on element 3! suitably pivoted at 32. Element 3| also carries flexible switch arms i5 and I5 respectively engageable with contacts 53 and i4. Spring 33 acts on the element 3| to automatically move the switch arms l5-lll to open-circuit position, as the heater cools. During heating, the upper end of element 28 is moved to the right, resulting in motion of the switch arms to circuit-closed position.

The armature for relay No. 1 is indicated at 40 and that of relay No. 2 is indicated at 4i. These armatures are biased to open by gravity, and each controls three contact arms operated in the man ner best shown in the diagram.' One of the contacts of relay No. 2 is an overlapping contact, the purpose of which is hereinafter explained. Armature 40 of relay No. 2 is pivoted at 40*.

Upon application of heat the heater element 4, the upper end of the bimetallic element 28 moves to the right and rotates the assembly, comprising compensating arm 30 and switch arms l5 and IS, in clockwise direction about the pivotal point 32. During such movement, arm l5 first engages contact I3, and then arm [5 engages contact i4. Upon de-energization of the heater coil 4, thermostatic element 28 begins to cool, its upper end moves to the left allowing the assembly to rotate in a counter-clockwise direction as the result of biasing action of spring 33, to first move arm I5 away from contact l4,- and after a time interval disengage arm l5 from contact 13. Compensating blade 30 is provided for maintaining timing action of the switch constant in spite of fluctuations in ambient temperature, in a manner known to this art.

Between therelays and mounted on a suitable bracket 42 is a ratchet wheel 43 having a stop pin 44 engageable with the bracket to limit ratchet wheel rotation at its initial position as before its ratcheting operation begins. This wheel is provided with a plurality of teeth indicated at 46, and with a peripheral radial groove 4! which is adapted to receive an extension 48 of the movable switch arm 49 cooperative with corresponding contact member 50 and biased to move automatically to switch open position. The extension normally engages the periphery of the ratchet wheel, and whn so engaged, the switch is held in closed position. with the extension, the switch arm 49 snaps to open position and the ratchet wheel 43 is held in this position, until manually released. A spring 5| acts to move the ratchet wheel to its initial position, as before the ratcheting operation has begun. The ratcheting action is controlled by both relays. Armature 40 of relay No. 1 has a bracket 55 having an extension 56 at the outer end of which is a laterally projecting pin 51 substantially parallel with the axis of rotation of the ratchet wheel. Pivoted as at 50 to the extension When the radial groove 41 registers There is no intention to limit the broader aspects 56 is a check-pawl arm 59 having pawl 60 adapted to engage a ratchet tooth to secure the ratchet wheel in advanced position after being brought to that position by the action of a driving pawl operated by relay No. 2. The outer end of arm 59 rests on pin 5?, by which pin its downward motion is initially prevented. Armature 4i of relay No. 2 has a bracket 65 to which is pivoted as at 66, a pawl arm 67, having pawl 68, by means of which the ratchet wheel is given a step-by-step motion, toward switch-release position. The outer end of arm 6'! rests upon pin 51, and when relay No. l is open the pawl arm 6'! is raised to inoperative position. When relay No. l closes, the check pawl .66 moves downwardly and rearwardly to operative position, and the ratcheting or driving pawl 69 oi? relay No. 2 is lowered to operative position, and conditioned so that on the first closure of relay No. 2, the ratchet 43 is advanced one tooth, against the action of the spring 5i. After this advance has been accomplished, the check pawl til of relay No. 1 engages the tooth to secure the ratchet wheel is against reverse rotation under the action of the spring. On the second closure of relay No. 2, the ratchet wheel is advanced another tooth, where it is again held by the check pawl. On the third closure of relay No. 2 the ratchet wheel is advanced another tooth, and at the end of the advance movement the groove 41 is brought itno register with the extension 48 of the switch arm 49, and the switch 3 automatically opens; thereafter the switch extension 48, cooperating with the groove 41?, latches the wheel 43 to prevent its counter-rotation to initial position under action of spring 50.

Additional means is provided for manually closing the safety switch after it has been automatically opened at the end of failure of ignition after repeated trial ignition periods. It will be noted that the switch arm extension 48 engages the side of the groove H of the ratchet wheel 43, to hold the wheel against automatic counterrotation after both relays open. Mounted on the bracket 42 which carries the ratchet wheel, is a barrel 'lil having therein aplunger H which projects at one end to be engaged by the finger of the operator, and which at the opposite end projects to engage the movable switch member 49. A spring 19 urges the plunger in a direction away from the switch arm 49. The plunger has an insulated portion l2, having a reduced terminal portion it which passes loosely through an opening F5 in the switch arm 49, the reduced extension 19 forming a shoulder 18 which engages the switch arm in a manner to move it sufficiently to withdraw the extension 48 from the radial groove ill of the ratchet wheel 43 and release the wheel for a return to its initial position. The terminal of the reduced portion 13 first engages the blade 5!! and moves it to maintain switch-open position, and then shoulder 16 engages blade 49,

moving it until the extension 48 is withdrawn from groove ll to release the ratchet wheel 43. After engagement of shoulder 16 with blade 49, the blades move in unison, in switch-open relation. After release of the ratchet wheel, and during reverse motion of element 12, to the position shown in Figure 4, the blades also move in unison in switch-open relation, until 48 engages the periphery of the wheel 43, after which on continued reverse motion of 12, blade 59 assumes the circuit-closed position shown.

It is conceivable that other mechanisms could be employed for opening the switch after ignition failure following repeated trial ignition periods.

of the invention to this particular feature, although certain of these details are claimed.

The flame responsive device, generally designated -5, herein has the form of a stack thermostat having two switches (cold contact 16 and hot contact l1) controllable by a single thermal means. This device is illustrated in Figures 5 and 6, and its application is shown in the diagram, Figure 7. The device is so constructed that on temperature rise, hot contact I! is closed prior to the opening of cold contact H3; in other words, so that the contacts are operated in overlapping relation on temperature rise. Upon temperature fall, that contact which was first to close on rise in temperature, opens before the closing of that contact which was last to open on temperature rise. In this instance, the hot contact closes prior to the breaking of the cold during temperature rise, and the hot contact is opened before the cold contact closes during temperature fall. Numeral indicates a shaft suitably mounted for rotation and 8! indicates a thermal element by which the shaft is rotated in opposite directions conformably to rise and fall in temperature. Suitably fixed to the shaft 80 is a toothed disk 82 and suitably rotatably mounted on the shaft is a disk 83. These disks are insulated from the shaft. Separately mounted on a suitable insulating base are contacts l6|1 in the form offlexible blades, and mounted on a common support and cooperative with respective contacts 16-41 are contact arms or blades 8485. These arms are biased to move to' circuit closed position respectively in opposite directions. Arm 84 is engaged and operated by the teeth of the rotatable disk 83. A control member 86 is engaged and operated by the teeth of the fixed disk 82, and this control member is adapted to hold the arm 85 normally in open position against its biased action, and the arm 85 is adapted to follow the control member 86 as the disk moves in counterclockwise direction.

A lost motion connection is provided between the disks 82-83, the disk 82 having a pin 88 which loosely traverses the slot 89 of the disk 83, said disk 83 having an adjustable plate 90 held in adjusted position by set screws. This plate provides a radial stop shoulder 9i against which the pin engages during clockwise motion of the disk 82, the opposite end 92 of the slot being engaged by the pin when the shaft moves in counterclockwise direction. By means of the plate, this lost motion connection is adjustable so that a timed interval may be provided during which the disk 83 is not rotated.

Associated with switch arm 84 is a spring arm 93 having a cam 94, and this arm 93 passes through an opening 95 of the switch arm 84. When arm 84 is moved sufficiently by disk 83, it cooperates with the cam to flex the spring arm. Just after the peak of the cam 9t is reached, the resilient action of the spring arm 93 causes the cam to quickly move the blade 84 to the corresponding circuit control position where it is held by the cam until after a predetermined degree of rotation of the disk 83 in an opposite direction. In this instance, the arm 84 is moved to circuitclosed position, on clockwise motion of disk 83, due to cooling of the thermostatic element.

The operation of the device in the present system is as follows, referring to Figure 6: As-

in counter-clockwise direction, due to this rise in temperature. During the first part of this rotation, the lost motion connection between the disks permits a movement of the fixed disk 82 without movement of the disk 83. The control member 86, therefore, moves to the right and the switch arm 85 follows it until this arm reaches switch-closed position. sure, the pin 88 which has been travelling in the slot 89, engages the stop 92 and on continued motion of the shaft in counter-clockwise direction, due to continued rise in temperature, the disk 83 begins to move in the same direction and arm 84 begins to move but does not open its contact until said arm has just passed beyond the peak of the cam, at which time the arm is suddenly snapped to switch-open position, where it is releasably locked in open position, by the cam. It is thus seen that on rise in temperature, the hot contact is closed before the cold contact is opened and, therefore, the contacts are overlappingly controlled. When the temperature falls, the direction of shaft rotation is reversed, and is clockwise. During the forepart of this motion, disk 83 is held against rotation as the result of engagement of its teeth with the arm 84 which is temporarily held from motion toward the left by cam 94. The first action is by the'disk 82 which moves the control member 86 against the switch arm 85 and opens the switch. During this movement, the pin 88' is moving in the slot 89 in adirection away from the stop 92 formed by the end of the slot, and after a timed interval, determined by stop spacing, the pin engages the stop 9| and the disk 83 begins to rotate, also in clockwise direction, resulting in movement of the switch arm 84, against the cam. This action closes switch l6, and further clockwise motion of the disk 63 results in the depression of the spring arm, and after movement of arm 84 to a point just beyond the peak of the cam the spring arm is suddenly released to result in a quick movement of the switch arm to condition it for a snap movement on subsequent rise in temperature. It is thus seen that on a fall in temperature, the hot contact is broken before the cold contact closes.

The function performed in this system by the flame responsive device above described (which provides overlapping contacts on temperature rise and non-overlapping contacts on temperature fall) is more fully explained under the headings Operation.

NORMAL Oraannon Ignition produced on first trial Assume a call for heat by the room thermostat and a closure at W, R, B. Relay No. 1 is closed through the following circuit: secondary of transformer 26, safety contact 3, W, R, B, time switch heater 4, contact Ill of relay No. 2, contact l6 of the flame responsive device, coil Hill of relay No. 1 to the opposite side of the secondary. The time switch now begins to move to the left under the action of its energized heating element. By

. closure of relay No. 1, contacts 6, I, and 8 are closed, the ignition means being activated through closure of contact 8. The circuit for the ignition means is as'follows: hot line, contact 8, ignition means I to the ground line. Contacts 6 and I complete a holding circuit for No. 1 relay as follows: one side of the secondary of the transformer 26, safety contact 3, W, R, 6, 1, heater 4, contact 10 of relay No. 2, contact l6 of the flame responsive device, I06 to the opposite After this clocontact 6 of relay No. 1, contacts I 3--i 4 of time switch, coil IOI of relay No. 2 to the opposite,

side of the secondary. On closure of relay No. 2, starting contact H) for relay N0. 1 is opened and heater 4 is deenergized, and a holding contact 9 for relay No. 1 is closed. On closure of No. 2 relay, the ratchet wheel is rotated one tooth in safety switch release direction. It will be noted that the burner motor is started by closure of contact 12, which marks the end of the preignition period. Contacts 9 and ID are overlappingly controlled so that contact 9 maintains a holding circuit through No. l relay. as follows: one side of the secondary, 3, W, R, 9, E6, M0 to the opposite side of the secondary. The fuel control means (motor) is now energized because on closure of relay No. 2, contact I2 was closed.

The contact II is now closed, and a holding circuit for relay No. 2 is established, which bridges the contact H of the time switch to maintain energization of the relay No. 2 until opening of the contact I3 of the time switch. This holding circuit is as follows: one side of the secondary of transformer 26, relay N0. 2, contact H, contact l3, contact 6, R, W, safety switch 3, to the opposite side of the secondary.

At this stage, (post ignition period) ignition means and motor are both energized, the ignition having been active for a predetermined preignition period.

The expression post-ignition period, as used herein, means that period following the preignition period, and at the beginning of which fuel feed is started and which fuel is delivered while the ignition means is active, and until ignition is successful or until a shut-down occurs due to failure to produce flame after repeated attempts.

It will now be assumed that combustion is successful. The flame-responsive device promptly closes contact IT. The closure of I! establishes a holding circuit for relay No. 2 as follows: one side of the transformer, coil; llll of relay No. 2, H, II, 9, R, W, safety switch 3, to the opposite side of the secondary. Contact l3 may now be opened, without effecting an opening of relay No. 2. When the flame responsive device has heated sufliciently to break contact 5, the circuit to relay No. 1 is opened, theignition means is de-energized and relay No. 2 remains energized. This breaking of IS occurs at the expiration of the post-ignition period which is determined by the setting of the flame responsive device. The burner is now normally operating with the motor running and flame present. When relay No. 1 drops out, the check pawl controlled thereby moves away from check position, and disengages the driving pawl, allowing the'wheel to move to its initial position.

In further explanation of the operation of the electro-thermal time switch: On heating contact I3 is first closed, and a time period thereafter contact I4 is closed. Both contacts l3 and H and are in the starting circuit of relay No. 2 but contact I 3 only is in the holding circuit, which circuit is: 26, H, H, l3, 6, R, W, 3, 26. Thus on cooling of the time switch mechanism, contact l4 opens a time period before contact l3 opens. When contact I3 opens, relay 2 is deenergized first closing contact I0 and then opening contact 9. Closure of contact I0 re-energlzes heater 4, but a distinct time interval intervenes before relay 2 is re-energized, due to the above noted fact that contact I4 is closed a time interval after contact I4 closes.

OPERATION 0N FAILURE TO PRODUCE FLAME As in the first case, on closure of the room thermostat, the ignition means and time switch heater are energized, and the ignition timing period begins. As soon as both contacts I3--I4 of the time switch have closed (end of pre-ignition timing period), relay No. 2 is energized to give the wheel 43 a first movement and the motor is energized, while ignition is maintained. On closure of relay No. 2, the circuit to the time switch heater is broken at contact I0, and a cooling motion of the time switch begins, to-time the post-ignition period. If flame is not produced before the time switch opens contact I3 at the end of this cooling period, in other words, if holding contact I! for relay No. 2 has not been closed at this time, relay No. 2 will open, and in so doing will again close the starting circuit for No. 1 relay at contact I0, and the time switch heater will again be energized for another timed trial ignition operation.

On closure of the time switch contact I4 at the end of this second trial ignition period, relay No. 2 will again be energized to give ratchet 43' a second movement, opening contact I0 and deenergizing the heater. The heater will now cool, to first open contact I4 and after a timed period will open to again de-energize relay No. 1, if flame is not produced before such opening. When relay No. 2 is energized for the third time, the ratchet wheel 43 is given a third movement which results in automatically opening the safety switch 3 to de-energize both relays, and resulting in the movement of the ratcheting pawls to release position, leaving the ratchet wheel locked and the safety switch open.

Inspection and repair is now in order, and after this has been attended to the movable switch element is manually moved to circuit closed position by the means previously described, and the ratchet wheel is released to assume its initial position.

It is, therefore, seen that means has been provided for obtaining a plurality of timed ignition periods at the end of which, if flame is not produced, the apparatus is locked against further automatic operation.

OPERA'rIoN ON FLAME FAILURE Arm SUCCESSFUL IGNITION On flame failure after successful ignition, (and while heat is being supplied and while the thermostat is closed) contact IT is opened, due to viously described and including safety switch 3,

room thermostat, heater 4, and contacts I0 and I6. This delayed closure period is for the purpose of allowing the natural draft to dissipate accumulated gases, to prevent explosion on -resumption of ignition. On closure of No. 1 relay,

a trial ignition operation is initiated (or'a series of such operations) in the manner previously described.

It is conceivable that other means than relays may be employed for controlling ignition and fuel feed, and that a single means may be thus employed, and that this single means may operate the ratcheting mechanism after each ignition failure, and that this means may be thermally controlled. We believe ourselves the first to use a thermally controllable timing means to bring about a plurality of trial ignition periods, and the first to operate a switch by a ratcheting device, in a system of this kind.

Figures 8 to 12, inclusive, illustrate a modification of the ratcheting mechanism, particularly designed to prevent momentum over-run of the ratchet wheel, at the end of any forward stroke of the pawl, due to rapid motion of the armature as it closes. The general arrangement-of the parts of the ratcheting means is substantially the same as previously described for Figures 1 to 4. inclusive. An important feature relates to means by which movement of the driving pawl, away from the wheel, at the end of the forward stroke, is prevented.

There are also certain features which relate to the manner of assembling the parts. One relates to the mounting of the ratcheting mechanism on a common support, instead of having the pawls (or pawl arms) mounted directly on the relay armatures. 7

The support for the ratcheting mechanism is indicated at I I0. The ratchet wheel is indicated at III and'the stop pin at H2. The spring for automatically moving the ratchet to initial position is indicated at H3. The movable switch arm of the safety or master switch 3 is indicated at H6 and the extension at 1.

Means for moving the extension I I! from notch or channel I20 to close the switch, is generally indicated at I22. This construction is not described in detail because it is substantially the same as that previously described.

The armature of relay No. 1 is indicated at I23 and that of relay No. 2 at I24. "I'he check pawloperating arm for relay No. 1 is indicated at I25 and the driving pawl-operating arm for relay No. 2 is indicated at I26. These pawl arms swing on a common pivot I21 carried by support H0. The pawl arm I25 has an angular extension I29 having at its inner terminal a laterally extending pin I30. Pivoted as at I3I to the arm I25 is a pawl I32 having a terminal bifurcation I33 normally disposed as shown in Figure 10. The tooth-engaging portion is indicated at I34. When relay No. l is closed as Shown in Figure 10, 334 is operatively conditioned as previously described for the other form.

An arm I35, secured to the armature I23 as at I38, is forked to provide projections I36, see dotted lines in Figure 10, cooperative with pin I31, carried by arm I25 to control the arm.

The arm I26 has pivoted at its upper end as at I a driving pawl I40. This pawl is best shown in Figure 12 in which figure the parts are positioned as at the end of the forward stroke, corresponding to closed position of the armature of relay No. 2. The tooth-engaging portion of the pawl is indicated at I43. The outer end of the arm I40 is bifurcated as shown to provide spaced upper and lower arms I44-I 45. Before relay No. 2 closes, see Figure 11, the upper arm I44 rests upon the pin I 30. The arm I45 is curved to provide an inclined plane indicated at M6, see Figure 12, adapted to engage the pin I30 to prevent pawl motion in a direction away from the ratchet wheel, at the end of the stroke. With I43 engaging a tooth and resting on inclined surface I41 between consecutive teeth, it is seen that, due to the direction of inclination of the surface I41, and to the engagement of the arm I45 with pin I 30, no forward motion of the wheel, due to momentum, can occur. The position shown in Figure 12 is assumed for each stroke.

An operating connection I48 similar to that of the connection I35 is provided between the armature I24 of relay No. 2 and the pin I49 of the pawl-operating arm I26.

Spring I50 acts to yieldably hold pawl I32 against pin I30.

We claim as our invention:

1. A heating system including a fuel feeder and means for controlling it, an igniter and means for controlling it, a safety switch adapted to render the system inoperative, and means controlled by the combined action of the fuel feeding and ignition control means for opening the safety switch after a-plurality of fuel feeding operations while the igniter is active.

2. A heating system including a fuel feeder and means'for controlling it, an igniter and means for controlling it, a safety switch adapted to render the system inoperative, means controlled by the combined action of the fuel feeding and ignition control means for opening the safety switch after a plurality of fuel feeding operations, and means for continuously maintaining igniter activation during and between the fuel feeding operations.

3. A heating system including a fuel feeder and means for controlling it, an igniter and means for controlling it, a safety switch adapted to render the system inoperative, means controlled by the combined action of the fuel feeding and ignition control means for opening the safety switch after a plurality of fuel feeding operations while the igniter is active, and means responsive to successful ignition adapted to render the igniter control means inoperative if flame is produced.

4. A heating system including a fuel feeder and means for controlling it, an igniter and means for controlling it, a safety switch adapted to render the system inoperative, means controlled by the combined action of the fuel feeding and ignition control means for opening the safety switch after a plurality of fuel feeding operations while the igniteris active, means responsive to successful ignition adapted to render the igniter control means inoperative if flame is produced, and thermostatic means adapted to control the .fuel feeder and igniter control means.

the fuel feeder controlling relay at the end of a.

predetermined timed period after energization of the igniter feeder controlling relay, and for temporarily deenergizing the fuel controlling relay after a predetermined timed period of energization, and means for preventing deenergization of said fuel feeder controlling relay if ignition is successful within the period for which it is timed to be deenergized.

6. A heating system including an igniter and a relay for controlling it, a fuel feeder and relay for controlling it, a safety switch for rendering the system inoperative, means controlled by the conjoint action of said relays for opening said safety switch after repeated energizations of the fuel feeder controlling relay, means for energizing the igniter controlling relay and for energizing the fuel feeder controlling relay at the end of a predetermined time after energization of the igniter controlling relay, and for temporarily deenergizing the fuel feeder controlling relay after a predetermined period of energization, said last named means including a thermally operable switch adapted to close a circuit when heated and a heater element adapted to be energized on energization of the igniter controlling relay, and to be de-energized on energization of the fuel feeder controlling relay.

7. A device of the class described including fuel feeding means, ignition means, a first relay adapted to control the ignition means, a second relay adapted to control the fuel feeding means, a safety switch and means controlling it by both relays to open it after a plurality of closing movements of the second relay while the first is closed, a flame responsive switch having first and second contacts and means overlappingly controlling them on temperature rise, a thermally operable time switch having first and second contacts, a heater for controlling said time switch, a room thermostat having first and second contacts, first and second contacts controlled by the first relay, first, second and third contacts controlled by the second relay, the first and second being overlappingly controlled, a starting circuit for said first relay including therein said safety switch, both contacts of said room thermostat, said heater, the second contact of said second relay, and the first contact of said flame responsive switch, a holding circuit for said first relay including therein said safety switch, the first contact of said room thermostat, the-first contact of said second relay, and the first contact of said flame responsive device, a starting circuit for said second relay including said safety switch, a contact of said room thermostat, the second contact of the first relay, and both contacts of the time switch, and a holding circuit for said second relay including said safety switch, the first contact of said room thermostat, the first contact of said second relay, the second contact of said flame responsive device, and the third contact of said second relay.

8. A control device comprising an element advanceable step-by-step from an initial to a final position, means biasing said element to initial position,ratchet driving means for advancing said stepby-step element, a relay for actuatingsaid ratchet mechanism, a temperature-responsive element, an electric heater for said temperature-responsive element, an energizing circuit for said relay controlled by the temperature responsive element, and an energizing circuit'for the heater including a switch controlledby the relay.

9. A control device comprising an element advanceable step-by-step from an initial to a final position,means biasing said element to initial position, ratchet driving means for advancing said step-by-step element, a relay for actuating said ratchet mechanism, a temperature-responsive element, anelectric heater for said temperav 2,070,118 ture-responsive element, an energizing circuit.

for said relay'controlled by the temperature-responsive element, a holding circuit for said relay controlled jointly by the temperature-responsive element and the relay, and an energizing circuit for the heater including a switch controlled by the relay.

10. A control device comprising an element advanceable step-by-step from an initial to a final position, means biasing said element to initial position, ratchet driving means for advancing said step-by-step element, a relay for actuating said ratchet mechanism, a temperature-responsive element, an electric heater for said temperature-responsive'element, an energizing circuit for said relay controlled by the temperature-responsive element, an energizing circuit for the heater including a switch controlled by. the relay, 2. releaser normally checking return of said stepby-step element,,a second relay acting to retract said releaser and having switch elements, and a circuit for the heater including a switch controlled by the first relay and a switch controlled by'the second relay.

1 1. A control device comprising an element advanceable step-by=step from an initial to a final position; means biasing said element to initial position, ratchet driving means for advancing said step-by-step element, a relay for'actuating said ratchet mechanism, a temperature-- responsive element, an electric heater for said temperature -responsive element, an energizing" .circuit for said relay controlled by the temperature-responsive element, a holding circuit for said relay controlled jointly by the temperature- .means, a safety switch for rendering the system inoperative, an element biased to initial position and advanceable step-by-step to a position for opening said safety switch, a releaser for checking return of said step-by-step element to initial position, electromagnetic means operative" when energized to move said relea'ser to its non-releasing position, a switch controlled by said electromagnetic means, an ignition circuit including said switch, timing means for intermittently actuating said step-by-step element and the fuel supply controlling means, a main control for operating said electromagnetic means and timing means upon a call forheat, and

means for maintaining operation of the fuel and advanceable step-by-step to'a position for opening said safety switch, a releaser for checking return of said step-by-step element to initial position, electromagnetic meansoperative when energized to move said releaser to its non-releasing position, a switch controlled by said electromagnetic means, an ignition circuit including said switch, a second electromagnetic means operable when energized to advance said step-by-step element a predetermined amount, electrical timing means for intermittently energizing said second electromagnetic means, a switch in circuit-with the fuel supply controlling means and moved to closed position upon energization of said second electromagnetic means, a main control switch for energizing the first electromagnetic means and timing means upon a demand for heat, and means responsive to the temperature of combustion for maintaining energization of said second electromagnetic means if combustion is successfully established.

14. In combination, a control system'comprising, fuel supply means, ignition means, hot and cold switches, means responsive to combustion conditions for opening said hot switch substantially immediately upon cessation of combustion and for closing said cold switch a delayed interval after opening of said hot switch and for opening said cold switch upon the establishment of combustion, a main control, means under the control of said main control and cold switch for repeatedly operating said fuel supply means in an attempt toestablish combustion, means controlled by saidmain control and hot switch for maintaining operation of the fuel supply means if combustion is established, and means for rendering the system inoperative until manual intervention if combustion is not established after a predetermined number of attempts.

15; A system of the class described, comprising, incombination, ignition means, a first relay in control of said ignition means, a first relay switch moved to closed position thereby when energized, fuel control means, a second relay in switches being overlappingly controlled, combustion responsive switching mechanism including hotand cold switches-overl'appin'gly controlled upon establishment of combustion, a main conof closing movements of saidsecondrelay while the first is closed, a thermal time switch and a heating element therefor, an initial energizing circuit for the first relay, and heating element including the main control switch, safety switch, second relay switch and cold switch in series, a holding circuit for the first relay and independent of the heating element including, the main control switch, safety switch, cold switch, and

first and third relay switches in series, anener- -gizing circuit for, the second relay controlled by the safety switch, main control switch and time 7 switch in series, and a holding circuit for the second relay "including the main control switch and hot switch in series.

FREDERICK s.= DENISON. e JOHN P. KRIECHBAUM. 

